Medical device

Abstract

A medical device for incising a substance inside a biological lumen. The medical device includes a tubular drive shaft that is rotatable, an intermediate portion connected to the drive shaft, at least one strut interlocked with the drive shaft, a tubular linear motion shaft inside of the drive shaft, and a tubular interlock portion. The strut is rotatable with the drive shaft and is expandable radially outward in response to outward expansion of the intermediate portion. The linear motion shaft is movable relative to the drive shaft in the axial direction to cause the strut to expand radially outward. The tubular interlock portion interlocks the drive shaft and the linear motion shaft while maintaining liquid-tight properties. The tubular interlock portion is stretchable in the axial direction.

What is claimed is: 
     
       1. A medical device for incising a substance inside a biological lumen, the medical device comprising:
 a tubular drive shaft that is rotatable about a rotary axis, the drive shaft possessing a distal portion, a proximal portion, and extending in an axial direction; 
 an intermediate portion connected to the distal portion of the drive shaft, the intermediate portion being expandable radially outward; 
 at least one strut interlocked with a distal portion of the drive shaft, the at least one strut being rotatable with the drive shaft, extending along the rotary axis and being expandable radially outward in response to radial outward expansion of the intermediate portion; 
 a tubular linear motion shaft inside the drive shaft, the linear motion shaft being movable relative to the drive shaft in the axial direction to cause the strut to expand radially outward, the linear motion shaft being rotatable together with the drive shaft, the linear motion shaft possessing a proximal portion; and 
 a tubular interlock portion that interlocks the proximal portion of the drive shaft and the proximal portion of the linear motion shaft while maintaining liquid-tight properties and is stretchable in the axial direction. 
 
     
     
       2. The medical device according to  claim 1 ,
 wherein the drive shaft comprises a gear portion receiving a rotary drive force to rotate the drive shaft, and the interlock portion is proximal to the gear portion of the drive shaft receiving the rotary drive force. 
 
     
     
       3. The medical device according to  claim 1 , wherein the interlock portion includes a plurality of members. 
     
     
       4. The medical device according to  claim 1 ,
 wherein the interlock portion is configured to absorb torsion due to misalignment occurring between the proximal portion of the drive shaft and the proximal portion of the linear motion shaft about the rotary axis. 
 
     
     
       5. The medical device according to  claim 1 ,
 wherein the interlock portion is a tubular body possessing a distal end and a proximal end, and the interlock portion tapers in the axial direction from the distal end to the proximal end of the interlock portion. 
 
     
     
       6. The medical device according to  claim 1 , further comprising:
 an inner tube inside of the linear motion shaft, the inner tube being configured not to restrain rotation of the drive shaft and the linear motion shaft.